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Journal of Experimental Biology 17,396-401 (1940)
Published by Company of Biologists 1940

Experimental Production of Functioning Reduplications--A Triple and a Functioning Quintuple Hindlimb in the Frog

WALTER BRANDT M.D.¹

¹ University of Birmingham

1. The supernumerary limbs were produced by the rotating and splitting methods applied to the hindlimb bud in tadpoles of early stages of development.

2. The two methods gave different results. Using the rotating method, the rotated bud may develop a limb or multiples of a limb inverted at 180° and a regenerated limb of normal position. Using the splitting method, two limbs in mirror symmetry may develop besides a regenerated limb.

3. The function of supernumerary limbs is two-fold and may consist either of co-ordinated and synchronous movements of fully developed limbs or parts of limbs or the function may be restricted to some retarded and imperfect movements.

4. There is a great variety of form, structure, rate of development and arrangement of the parts of the multiples, to which a special function is related. One animal may show perfect co-ordinated movements of fully developed reduplicated limbs (case 841), another may show restricted co-ordinated movements (case 1220), while others may show co-ordinated movements of parts of other supernumerary limbs (cases 1251, 1284).

5. The co-ordinated movements in experimentally produced supernumerary hindlimbs of the frog are to be regarded as an "integration of a series of reflexes", and they are related to the same reflex mechanism which acts in the normal ambulatory cycle of the toad (Gray & Lissmann, 1940). The retarded and imperfect movements in some supernumerary deformities indicate that disturbances of the normal cycle are not the expression of a centrally determined rhythm.

Note:

The work was aided by a Grant of the Medical Faculty Research Fund and the Sir Charles Hyde Fund of the University of Birmingham. The author wishes to tender his thanks to the Research Committee of the University for granting these funds.